As is well known to those skilled in the art, the leavening of bakery products is accomplished by liberation of carbon dioxide with the dough or batter during its preparation and in the early stages of baking. The carbon dioxide serves the purpose of lightening the baked product, giving it a finer, smoother texture and increasing its volume.
The rate of gas evolution and the uniformity thereof is an important consideration, determining largely the density and textural qualities which will be imparted to the final baked product. This rate and uniformity must be controlled within rather narrow limits in order to achieve the desired results. Moreover, leavening requirements differ appreciably among the various baked goods, for each of these demands particular conditions of evolution to insure highest quality products.
Typically, a leavening system is composed of one or more leavening acids and an alkaline substance capable of releasing carbon dioxide upon reaction with the leavening acid. A large number of leavening acids are known in the baking art and are widely used for this purpose at the present time. Essentially, the only gas-producing agents now in practical use are the baking carbonates, e.g., sodium bicarbonate.
While the current basic leavening processes, for example, the present commercial system of a leavening acid and bicarbonate is satisfactory, the use of the leavening acids, however, are attended by a high amount of process variables, the elimination of which is the object of much experimentation as reflected by voluminous prior art.
For example, the rate of CO.sub.2 evolution in a baking preparation is primarily controlled by manipulating the reactivity of the acid component used. Further, it is very desirable that the reactivity of a leavening acid be predictable and unchanging. With leavening acids the speed of reaction has been set at the desired level by means of special techniques of manufacture. Unfortunately, the reactivity has been found to change thereafter when the acid is exposed to climatic conditions upon storage. The speed of reaction usually accelerates due to storage at high temperatures and/or high humidities. Instability is a disturbing problem with leavening acids which has also been given much attention in the prior art.
For example, U.S. Pat. No. ,170,270 discloses a slow reacting leavening system, i.e., baking powder, which improved the yield of carbon dioxide produced. The baking powder comprised phytic acid mixed with sodium bicarbonate and starch.
U.S. Pat. No. 3,034,899 discloses an improvement in the stability of leavening acids by adding a finely divided calcium salt to sodium acid pyrophosphate after it has been manufactured. The required quantity of calcium salt is usually dry-mixed with the acid, and brought into intimate contact by a suitable mixing or blending apparatus. The patent discloses that when the calcium compound is mixed into the sodium acid pyrophosphate, the two compounds become intimately associated which apparently precludes the deteriorating effects of storage at atmospheric conditions.
U.S. Pat. No. 4,196,26 discloses that calcium-treated sodium aluminum phosphate exhibits improved handling characteristics and is useful as a leavening agent in moist doughs and liquid complex aluminum phosphate with a calcium compound followed by granulating the calcium-treated product while drying. Complex aluminum phosphate granules with at least a calcium rich outer surface result.
U.S. Pat. No. 4,741,917 discloses that the stability of alkali metal acid pyrophosphates employed as leavening acids an be improved and provide sufficient leavening to provide a final product of desirable characteristics without using calcium ions. The invention is achieved by blending an alkali metal and pyrophosphate with an oxide or hydroxide of magnesium. The combination of the alkali metal acid pyrophosphate leavening acid and the oxide or hydroxide of magnesium provides product stability. It also discloses there is no "calcium ion effect" and the magnesium compounds are essentially insoluble.
It is apparent that most leavening systems heretofore known and described in the prior art are concerned with and define improved chemical leavening acids employed in leavening systems. It is also apparent that there is a need to improve the chemical leavening systems currently available, and, consequently, improve the baking compositions they are employed in.
Accordingly, it is an object of this invention to provide improved baked products which employ leavening systems containing one or more leavening acids and chemical leavening bases.
It is another object of this invention to provide improved baked products using chemical leavening bases which provide better leavening gas retention and efficiency for improved uniformity in the baked product cell structure.
It is also an object of this invention to provide improved baked products by increasing bakery product volume per unit of chemical leavening agents employed.
It is a further object of this invention to provide improved baked products by imparting a more tender "mouth feel" to the leavened baked products.
These and other objects will become apparent from the following detailed description.